diff --git a/python/tako/core/compiler/__init__.py b/python/tako/core/compiler/__init__.py
index 08591b5..44d10c6 100644
--- a/python/tako/core/compiler/__init__.py
+++ b/python/tako/core/compiler/__init__.py
@@ -38,6 +38,7 @@ def compile_proto(
     if isinstance(comp_constants, list):
         return comp_constants
 
+    # Q: Are conversions affected by skippable hash variants in any meaningful way?
     comp_conversions = conversions.compile(
         proto.name, proto.conversions, comp_types.types
     )
diff --git a/python/tako/core/compiler/types/__init__.py b/python/tako/core/compiler/types/__init__.py
index e9d81d0..6274156 100644
--- a/python/tako/core/compiler/types/__init__.py
+++ b/python/tako/core/compiler/types/__init__.py
@@ -45,6 +45,11 @@ def compile(
         if errors:
             return errors
 
+    # Builds up a map from master to slave fields. This is the sort of reverse
+    # action that takes place during parsing. At parse time, a Seq's length is first
+    # read, then the sequence length is known. At build time, the Seq is built first
+    # and the previous field is later populated. This master_field_map seems focused
+    # on the "builder" problem
     master_field_map = master_fields.run(lowered, type_order)
     if isinstance(master_field_map, list):
         return master_field_map
diff --git a/python/tako/core/compiler/types/fuse.py b/python/tako/core/compiler/types/fuse.py
index c7abbdf..7c4f62f 100644
--- a/python/tako/core/compiler/types/fuse.py
+++ b/python/tako/core/compiler/types/fuse.py
@@ -100,6 +100,7 @@ def visit_fixed_variant(self, variant: mir.FixedVariant) -> lir.RootType:
             trivial=self.tmap[variant.name],
             name=variant.name,
             digest=self.digest_map[variant.name],
+            len_type=checked_cast(lir.Int, variant.len_type.accept(self)) if variant.len_type else None,
             tag_type=checked_cast(lir.Int, variant.tag_type.accept(self)),
             tags={
                 checked_cast(lir.Struct, sr.accept(self)): value
diff --git a/python/tako/core/compiler/types/hash_expand.py b/python/tako/core/compiler/types/hash_expand.py
index f2298de..8a13ef1 100644
--- a/python/tako/core/compiler/types/hash_expand.py
+++ b/python/tako/core/compiler/types/hash_expand.py
@@ -16,7 +16,7 @@
 import dataclasses
 from tako.core.compiler.types import mir
 from tako.core.error import Error
-from tako.core.repr_str import ReprStr
+from tako.core.repr_str import ShallowReprStr
 from tako.util.qname import QName
 import hashlib
 
@@ -58,20 +58,20 @@ class HashExpand(
     mir.VariantVisitor[t.Union[mir.FixedVariant, Error]],
 ):
     types: t.Dict[QName, mir.RootType]
-
-    def digest(self, rt: mir.RootType) -> Digest:
-        x = rt.accept(ReprStr(self.types))
+    
+    def shallow_digest(self, rt: mir.RootType) -> Digest:
+        x = rt.accept(ShallowReprStr(self.types))
         return Digest(repr_str=x, repr_hash=sha256hex(x))
 
     def visit_struct(self, root: mir.Struct) -> t.Union[HashExpandResult, Error]:
-        return HashExpandResult(self.digest(root), None)
+        return HashExpandResult(self.shallow_digest(root), None)
 
     def visit_variant(self, root: mir.Variant) -> t.Union[HashExpandResult, Error]:
         fixed = root.accept_v(self)
         if isinstance(fixed, Error):
             return fixed
         else:
-            return HashExpandResult(self.digest(fixed), fixed)
+            return HashExpandResult(self.shallow_digest(fixed), fixed)
 
     def visit_fixed_variant(
         self, variant: mir.FixedVariant
@@ -87,7 +87,7 @@ def visit_hash_variant(
         tag_map: t.Dict[mir.StructRef, int] = {}
         inv_tag_map: t.Dict[int, mir.StructRef] = {}
         for type_ in variant.types():
-            hash_hex = self.digest(type_.resolve(self.types)).repr_hash
+            hash_hex = self.shallow_digest(type_.resolve(self.types)).repr_hash
             short = int(hash_hex[:tag_width_hex_digits], 16)
             if short in inv_tag_map:
                 return Error(
@@ -96,7 +96,7 @@ def visit_hash_variant(
             tag_map[type_] = short
             inv_tag_map[short] = type_
 
-        return mir.FixedVariant(variant.name, variant.tag_type, tag_map)
+        return mir.FixedVariant(variant.name, variant.tag_type, tag_map, variant.len_type)
 
     def visit_enum(self, root: mir.Enum) -> t.Union[HashExpandResult, Error]:
-        return HashExpandResult(self.digest(root), None)
+        return HashExpandResult(self.shallow_digest(root), None)
diff --git a/python/tako/core/compiler/types/lir.py b/python/tako/core/compiler/types/lir.py
index 8ed8729..969d2b2 100644
--- a/python/tako/core/compiler/types/lir.py
+++ b/python/tako/core/compiler/types/lir.py
@@ -147,6 +147,7 @@ class MasterField:
 @dataclasses.dataclass(frozen=True)
 class Variant(RootType):
     tag_type: Int
+    len_type: Optional[Int]
     tags: t.Dict[Struct, int] = dataclasses.field(compare=False)
 
     def accept_rtv(self, visitor: RootTypeVisitor[T]) -> T:
diff --git a/python/tako/core/compiler/types/lower.py b/python/tako/core/compiler/types/lower.py
index 123cb85..2caddeb 100644
--- a/python/tako/core/compiler/types/lower.py
+++ b/python/tako/core/compiler/types/lower.py
@@ -49,18 +49,23 @@ def visit_variant_def(self, type_: pt.VariantDef) -> mir.RootType:
                 checked_cast(mir.StructRef, struct.accept(Lower())): value
                 for struct, value in type_.variants.items()
             },
+            False
         )
 
     def visit_hash_variant_def(self, type_: pt.HashVariantDef) -> mir.RootType:
+        # Cast to the mir int types
+        mir_tag_type = checked_cast(mir.Int, type_.tag_type.accept(Lower()))
+        mir_len_type = checked_cast(mir.Int, type_.len_type.accept(Lower())) if type_.len_type else None
         return mir.HashVariant(
             type_.qualified_name(),
-            checked_cast(mir.Int, type_.tag_type.accept(Lower())),
+            mir_tag_type,
             set(
                 [
                     checked_cast(mir.StructRef, struct.accept(Lower()))
                     for struct in type_.hash_types
                 ]
             ),
+            mir_len_type
         )
 
 
@@ -88,6 +93,7 @@ def visit_detached_variant(self, type_: pt.DetachedVariant) -> mir.Type:
         return mir.DetachedVariant(
             mir.VariantRef(type_.variant.qualified_name()),
             mir.FieldReference(type_.tag.name),
+            False
         )
 
     def visit_virtual(self, type_: pt.Virtual) -> mir.Type:
@@ -103,4 +109,4 @@ def visit_variant_def(self, type_: pt.VariantDef) -> mir.Type:
         return mir.VariantRef(type_.qualified_name())
 
     def visit_hash_variant_def(self, type_: pt.HashVariantDef) -> mir.Type:
-        return mir.VariantRef(type_.qualified_name())
+        return mir.HashVariantRef(type_.qualified_name())
diff --git a/python/tako/core/compiler/types/master_fields.py b/python/tako/core/compiler/types/master_fields.py
index 401dcbb..b02fe81 100644
--- a/python/tako/core/compiler/types/master_fields.py
+++ b/python/tako/core/compiler/types/master_fields.py
@@ -28,7 +28,6 @@ class MasterField:
     master_field: str
     key_property: KeyProperty
 
-
 @dataclasses.dataclass(frozen=True)
 class DeterminedField:
     determined_field: str
@@ -79,7 +78,7 @@ def visit_enum(
 
 # Map from a field A to a field B where the value of A (slave field) is determined by the the value
 # of field B (master field).
-# For example, if a struct has these fields: {"len": li32, "data", Seq(li32, this.len)},
+# For example, if a struct has these fields: {"len": li32, "data": Seq(li32, this.len)},
 # then this function would return {"len": "data"} because the value of len is determined
 # by the value in data.
 # This is needed for generating builders: should a given field be included in the generated
diff --git a/python/tako/core/compiler/types/mir.py b/python/tako/core/compiler/types/mir.py
index 4339cbf..a259055 100644
--- a/python/tako/core/compiler/types/mir.py
+++ b/python/tako/core/compiler/types/mir.py
@@ -83,6 +83,7 @@ def visit_hash_variant(self, variant: HashVariant) -> T:
 @dataclasses.dataclass(frozen=True)
 class FixedVariant(Variant):
     tags: t.Dict[StructRef, int]
+    len_type: t.Optional[Int]
 
     def types(self) -> t.Iterable[StructRef]:
         return self.tags.keys()
@@ -94,6 +95,7 @@ def accept_v(self, visitor: VariantVisitor[T]) -> T:
 @dataclasses.dataclass(frozen=True)
 class HashVariant(Variant):
     hash_types: t.Set[StructRef]
+    len_type: t.Optional[Int]
 
     def types(self) -> t.Iterable[StructRef]:
         return self.hash_types
@@ -280,11 +282,11 @@ def accept(self, visitor: LengthVisitor[T]) -> T:
 class DetachedVariant(Type):
     variant: VariantRef
     tag: FieldReference
+    is_hash_tag: bool
 
     def accept(self, visitor: TypeVisitor[T]) -> T:
         return visitor.visit_detached_variant(self)
 
-
 @dataclasses.dataclass(frozen=True)
 class Virtual(Type):
     inner: Type
@@ -338,6 +340,15 @@ def resolve(self, context: t.Dict[QName, RootType]) -> Variant:
     def accept_r(self, visitor: RefVisitor[T]) -> T:
         return visitor.visit_variant_ref(self)
 
+@dataclasses.dataclass(frozen=True)
+class HashVariantRef(VariantRef):
+    def resolve(self, context: t.Dict[QName, RootType]) -> Variant:
+        return checked_cast(Variant, context[self.name])
+
+    def accept_r(self, visitor: RefVisitor[T]) -> T:
+        # TODO clean up this type warning
+        return visitor.visit_variant_ref(self)
+
 
 @dataclasses.dataclass(frozen=True)
 class EnumRef(Ref):
diff --git a/python/tako/core/compiler/types/size.py b/python/tako/core/compiler/types/size.py
index 5652ac5..6275a48 100644
--- a/python/tako/core/compiler/types/size.py
+++ b/python/tako/core/compiler/types/size.py
@@ -63,8 +63,13 @@ def visit_struct(self, root: mir.Struct) -> RootSizeResult:
 
     def visit_variant(self, root: mir.Variant) -> RootSizeResult:
         target_size: t.Optional[st.Constant] = None
+        # Mark
+        if isinstance(root, mir.FixedVariant) and root.len_type:
+            print(f"Detected variant with embedded length: {root.name}")
+            return RootSizeResult(st.Dynamic(), None)
         for sr in root.types():
             size = self.size_map[sr.name].size
+            print(f"Contained size of {root.name} member {sr.name} is {size}")
             if not isinstance(size, st.Constant):
                 return RootSizeResult(st.Dynamic(), None)
             if target_size is None:
diff --git a/python/tako/core/compiler/types/variant_expand.py b/python/tako/core/compiler/types/variant_expand.py
index 99d0222..4b17a6d 100644
--- a/python/tako/core/compiler/types/variant_expand.py
+++ b/python/tako/core/compiler/types/variant_expand.py
@@ -34,11 +34,17 @@ class VariantExpand(mir.RootTypeVisitor[t.Optional[mir.Struct]]):
     def visit_struct(self, root: mir.Struct) -> t.Optional[mir.Struct]:
         new_fields: t.Dict[str, mir.Type] = {}
         for fname, ftype in root.fields.items():
-            if isinstance(ftype, mir.VariantRef):
+            if isinstance(ftype, mir.HashVariantRef):
                 new_fname = f"{fname}_injected_key_"
                 new_fields[new_fname] = ftype.resolve(self.types).tag_type
                 new_fields[fname] = mir.DetachedVariant(
-                    variant=ftype, tag=mir.FieldReference(new_fname)
+                    variant=ftype, tag=mir.FieldReference(new_fname), is_hash_tag = True
+                    )
+            elif isinstance(ftype, mir.VariantRef):
+                new_fname = f"{fname}_injected_key_"
+                new_fields[new_fname] = ftype.resolve(self.types).tag_type
+                new_fields[fname] = mir.DetachedVariant(
+                    variant=ftype, tag=mir.FieldReference(new_fname), is_hash_tag = False
                 )
             else:
                 new_fields[fname] = ftype
diff --git a/python/tako/core/repr_str.py b/python/tako/core/repr_str.py
index ecccdce..3e7d528 100644
--- a/python/tako/core/repr_str.py
+++ b/python/tako/core/repr_str.py
@@ -120,3 +120,91 @@ def visit_enum(self, root: mir.Enum) -> str:
         pairs = sorted([(value, name) for name, value in root.variants.items()])
         variants = ",".join([f"{value}={name}" for value, name in pairs])
         return f"Enum(name={root.name},underlying={root.underlying_type.accept(self)},variants={{{variants}}})"
+
+## This is used to construct the shallow hash. 
+@dataclasses.dataclass
+class ShallowReprStr(
+    mir.RootTypeVisitor[str],
+    mir.VariantVisitor[str],
+    mir.SeqTypeVisitor[str],
+    mir.LengthVisitor[str],
+):
+    types: t.Dict[QName, mir.RootType]
+
+    def visit_int(self, type_: mir.Int) -> str:
+        return f"Int(width={type_.width},sign={type_.sign.name},endianness={type_.endianness.name})"
+
+    def visit_float(self, type_: mir.Float) -> str:
+        return f"Float(width={type_.width},endianness={type_.endianness.name})"
+
+    def repr_field_reference(self, fr: mir.FieldReference) -> str:
+        return f"FieldReference(name={fr.name})"
+
+    def visit_seq(self, type_: mir.Seq) -> str:
+        # Note that the repr is done on the type before seq reduce
+        # -- there is only Seq, but not List, Vector, or Array.
+        # This is deliberate - the representation of the type is the intended to
+        # be a representation that is as simple as possible, but conveys everything
+        # needed to parse or serialize a type from a wire representation.
+        # List, Vector, and Array do not impact the wire representation, and hence
+        # are not used.
+        length = type_.length.accept(self)
+        return f"Seq(inner={type_.inner.accept(self)},length={length})"
+
+    def visit_unbound_seq(self, type_: mir.UnboundSeq) -> str:
+        raise InternalError()
+
+    def visit_fixed_length(self, length: mir.FixedLength) -> str:
+        return f"{length.length}"
+
+    def visit_variable_length(self, length: mir.VariableLength) -> str:
+        return self.repr_field_reference(length.length)
+
+    def visit_detached_variant(self, type_: mir.DetachedVariant) -> str:
+        variant = type_.variant.resolve(self.types)
+        return f"DetachedVariant(variant={variant.accept(self)},tag={self.repr_field_reference(type_.tag)})"
+
+    def visit_virtual(self, type_: mir.Virtual) -> str:
+        # Virtual types contribute to the hash just like normal types, even though they have no
+        # effect on the wire representation. They allow a type to represent that there is
+        # some other data on the wire related to it -- virtual fields are parsed
+        # using the context of the rest of the type.
+        return f"Virtual(inner={type_.inner.accept(self)})"
+
+    def visit_ref(self, type_: mir.Ref) -> str:
+        return type_.resolve(self.types).accept(self)
+
+    def visit_struct(self, root: mir.Struct) -> str:
+        # Including the name of the fields is critical -- otherwise the struct Foo { x: int, y: int }
+        # is the same as the struct Foo { y: int, x: int }.
+        # Names provide meaning to fields.
+        # Note that no derrived information, like the size or offset of fields is included. That could all
+        # be computed from this and is extraneous.
+        l = []
+        for name, type_ in root.fields.items():
+            if isinstance(type_, mir.DetachedVariant) and type_.is_hash_tag:
+                l.append(f"{name}=HashVariant")
+            else:
+                l.append(f"{name}={type_.accept(self)}")
+        fields = ",".join(l)
+        return f"Struct(name={root.name},fields={{{fields}}})"
+
+    def visit_variant(self, root: mir.Variant) -> str:
+        return root.accept_v(self)
+
+    def visit_fixed_variant(self, root: mir.FixedVariant) -> str:
+        # Sort the variant by tag to ensure order doesn't matter
+        pairs = sorted([(tag, sr) for sr, tag in root.tags.items()])
+        variants = ",".join(
+            [f"{tag}={value.resolve(self.types).accept(self)}" for tag, value in pairs]
+        )
+        return f"Variant(name={root.name},tag_type={root.tag_type.accept(self)},variants={{{variants}}})"
+
+    def visit_hash_variant(self, root: mir.HashVariant) -> str:
+        raise InternalError()
+
+    def visit_enum(self, root: mir.Enum) -> str:
+        # Like variant
+        pairs = sorted([(value, name) for name, value in root.variants.items()])
+        variants = ",".join([f"{value}={name}" for value, name in pairs])
+        return f"Enum(name={root.name},underlying={root.underlying_type.accept(self)},variants={{{variants}}})"
diff --git a/python/tako/core/sir.py b/python/tako/core/sir.py
index 6836375..7a70d93 100644
--- a/python/tako/core/sir.py
+++ b/python/tako/core/sir.py
@@ -23,7 +23,6 @@
 kir = constants.lir
 cir = conversions.lir
 
-
 @dataclasses.dataclass(frozen=True)
 class Protocol:
     name: QName
diff --git a/python/tako/core/types.py b/python/tako/core/types.py
index 20743d5..e7d32e2 100644
--- a/python/tako/core/types.py
+++ b/python/tako/core/types.py
@@ -268,6 +268,7 @@ def make_variant(variants: t.Dict[StructDef, int]) -> VariantDef:
 class HashVariantDef(RootType):
     tag_type: Int
     hash_types: t.List[StructDef]
+    len_type: t.Optional[Int]
 
     def accept(self, visitor: TypeVisitor[T]) -> T:
         return visitor.visit_hash_variant_def(self)
@@ -275,19 +276,27 @@ def accept(self, visitor: TypeVisitor[T]) -> T:
     def accept_rtv(self, visitor: RootTypeVisitor[T]) -> T:
         return visitor.visit_hash_variant_def(self)
 
-
 class HashVariantHelper:
     def __getitem__(
         self, tag_type: Int
     ) -> t.Callable[[t.List[StructDef]], HashVariantDef]:
         def make_hash_variant(hash_types: t.List[StructDef]) -> HashVariantDef:
-            return HashVariantDef(tag_type, hash_types)
+            return HashVariantDef(tag_type, hash_types, None)
+
+        return make_hash_variant
+
+class SkippableHashVariantHelper:
+    def __getitem__(
+            self, tag_len_type: t.Tuple[Int, ...]
+    ) -> t.Callable[[t.List[StructDef]], HashVariantDef]:
+        def make_hash_variant(hash_types: t.List[StructDef]) -> HashVariantDef:
+            return HashVariantDef(tag_len_type[0], hash_types, tag_len_type[1])
 
         return make_hash_variant
 
 
 HashVariant = HashVariantHelper()
-
+SkippableHashVariant = SkippableHashVariantHelper()
 
 @dataclasses.dataclass(eq=False)
 class Seq(Type):
diff --git a/python/tako/generators/lsir/lsir.py b/python/tako/generators/lsir/lsir.py
index 6dc1913..f86379d 100644
--- a/python/tako/generators/lsir/lsir.py
+++ b/python/tako/generators/lsir/lsir.py
@@ -46,6 +46,7 @@ def generate_into(self, proto: Protocol, out_dir: Path, args: t.Any) -> None:
         with (out_dir / Path(str(proto.name) + ".json")).open("w") as out:
             json.dump(dform, out, indent=4)
 
+    # TODO this should produce a real value
     def list_outputs(
         self, proto_qname: QName, args: t.Any
     ) -> t.Generator[Path, None, None]:
@@ -104,6 +105,7 @@ def visit_variant(self, root: tir.Variant) -> t.Dict[str, t.Any]:
             root,
             {
                 "tag_type": root.tag_type.accept(TypeLsir()),
+                "len_type": root.len_type.accept(TypeLsir()) if root.len_type else None,
                 "variants": {
                     f"{struct.name}": value for struct, value in root.tags.items()
                 },
diff --git a/python/test_types/actor/__init__.py b/python/test_types/actor/__init__.py
new file mode 100644
index 0000000..aa37bc0
--- /dev/null
+++ b/python/test_types/actor/__init__.py
@@ -0,0 +1,9 @@
+from test_types.bakery import Bakery
+from test_types.bakery.v1 import V1
+from test_types.bakery.v2 import V2
+
+class BakeryActor:
+    ## TODO fix field access
+    ## TODO fix variant access
+    ## Today
+    Produces = [Bakery.Packet.payload[V2.Message]]
diff --git a/python/test_types/actor/actor_compiler.py b/python/test_types/actor/actor_compiler.py
new file mode 100644
index 0000000..1637f34
--- /dev/null
+++ b/python/test_types/actor/actor_compiler.py
@@ -0,0 +1,29 @@
+import importlib
+from test_types.actor import BakeryActor
+
+module = "test_types.actor"
+
+live_module = importlib.import_module(module)
+
+a = BakeryActor.Produces[0]
+
+def print_keys(a):
+    [print(k) for k, v in a.__dict__.items()]
+print("*******************************************************************")
+print("*******************************************************************")
+print("*******************************************************************")
+print("*******************************************************************")
+print("*******************************************************************")
+print("Produces")
+print(a)
+## This synatx has to be better
+print("Version1")
+print_keys(BakeryActor.Produces[0].fields['payload'])
+print("Version2")
+print(BakeryActor.Produces[0].payload)
+# b = BakeryActor.Consumes[0]
+# 
+# print("Consumes")
+# print(b)
+
+
diff --git a/python/test_types/bakery/v4.py b/python/test_types/bakery/v4.py
index 935dd40..d77ace1 100644
--- a/python/test_types/bakery/v4.py
+++ b/python/test_types/bakery/v4.py
@@ -27,9 +27,11 @@ class V4(Protocol):
         # Frosting flavor is actually the most important
         # I can't believe I forgot it
         frosting_flavor=Flavor,
+        # Forgot about the number of sprinkles
+        # sprinkle_quantity=li32,
     )
     CakeOrder = Struct(layers=li32, shape=Shape, flavor=Flavor)
-    Order = Variant[u8]({CupcakeOrder: 0, CakeOrder: 1})
+    Order = HashVariant[u8]([ CupcakeOrder, CakeOrder])
 
     ErrorResponse = Struct()
     NewOrderRequest = Struct(name_len=u8, name=Seq(i8, this.name_len), order=Order)
@@ -47,14 +49,3 @@ class V4(Protocol):
         }
     )
     Message = Struct(msg=MessageVariant)
-
-    conversions = [
-        ConversionsFromPrior(
-            Prior,
-            VariantConversion(
-                src=MessageVariant,
-                target=Prior.MessageVariant,
-                mapping={CancelOrderRequest: None, CancelOrderResponse: None},
-            ),
-        )
-    ]
diff --git a/python/test_types/organism.py b/python/test_types/organism.py
new file mode 100644
index 0000000..b9cf1e6
--- /dev/null
+++ b/python/test_types/organism.py
@@ -0,0 +1,15 @@
+from tako.core.types import *
+
+class Organism(Protocol):
+    Felidae = Struct(num_lives=i8)
+    Canidae = Struct(balls_caught=i8)
+    Mammalia = HashVariant[li32]([Felidae, Canidae])
+    Chordata = Struct(family=Mammalia, symmetry=i8)
+
+    Phylum = HashVariant[li32]([Chordata])
+    Animalia = Struct(motility_type=i8, phylum=Phylum)
+    # Attempt to make a dynamic length member of a hash variant, does it embed the length somehow?
+    Plantae = Struct(seed_count=li32, seeds = Seq(i8, this.seed_count))
+
+    Kingdom = SkippableHashVariant[li32, u8]([Animalia, Plantae])
+    Organism = Struct(kingdom=Kingdom)
diff --git a/shallow_hash.txt b/shallow_hash.txt
new file mode 100644
index 0000000..bbb43ef
--- /dev/null
+++ b/shallow_hash.txt
@@ -0,0 +1,31 @@
+[](const ::test_types::bakery::v4::Message&) { return static_cast<::std::uint32_t>(UINT32_C(2458638600)); }
+
+This is the hash of a v4 message, which inside has a hash variant. Hopefully it changes when i add to the inner HV
+
+[](const ::test_types::bakery::v4::Message&) { return static_cast<::std::uint32_t>(UINT32_C(3267984003)); }
+
+Indeed it does.
+
+I made ShallowReprHash. This might not be the most efficient way to do it but initially I just want to see it preserve the hashes
+
+[](const ::test_types::bakery::v4::Message&) { return static_cast<::std::uint32_t>(UINT32_C(2458638600)); }
+
+Seems like it's back to the old hash when I remove the new sprinkle_quantity from the cupcakeorder, great.
+
+Ok that was more work than expected, but before:
+
+  5             [](const ::test_types::bakery::v4::Message&) { return static_cast<::std::uint32_t>(UINT32_C(390615788)); }
+
+after changing a field on a struct only present in an HV
+  5             [](const ::test_types::bakery::v4::Message&) { return static_cast<::std::uint32_t>(UINT32_C(390615788)); }
+
+after changing a field on a struct elsewhere in v4
+::std::uint32_t tag() const {                                                                                                                                
+  1         return match(
+  2             [](const ::test_types::bakery::v2::Message&) { return static_cast<::std::uint32_t>(UINT32_C(3831964682)); },
+  3             [](const ::test_types::bakery::v1::Message&) { return static_cast<::std::uint32_t>(UINT32_C(2782154402)); },
+  4             [](const ::test_types::bakery::v3::Message&) { return static_cast<::std::uint32_t>(UINT32_C(716972100)); },
+  5             [](const ::test_types::bakery::v4::Message&) { return static_cast<::std::uint32_t>(UINT32_C(1691428639)); }
+  6         );
+
+after changing a field on a struct elsewhere in v2